Features of the hemostasis system in polycythemia vera in children

Patients with polycythemia vera (PV) are at an increased risk for thrombosis. Abnormalities in coagulation parameters and global hemostasis tests can help with hypercoagulation recognition in PV. The purpose of this research was to analyze the features of changes in laboratory parameters of the hemostasis system in pediatric patients with PV. Materials and methods used: a single-center retrospective cohort study of clinical records of 32 (11 (35%) girls/21 (65%) boys aged 11.5 [0.8; 17.5] y/o) pediatric (all under the age of 18 y/o) PV patients who were admitted at the National Scientific and Practical Center for Pediatric Hematology, Oncology and Immunology named after Dmitry Rogachev (Moscow, Russia) in Jan. 2012-June 2024 was conducted. Laboratory parameters were determined prior to the beginning of the antiplatelet and cytoreductive therapy. Results: in 20 (62.5%) and 4 (12.5%) patients, mutations in the JAK2V617F and JAK2 ex 12 genes were detected, respectively, the remaining 8 (25%) children were JAK2-negative. In total, there were 8 (72%) JAK2-positive girls and 15 (71%) boys; gender did not statistically significantly affect the presence of a driver mutation (p=0.939). Both the median and the mean values of the main parameters of the blood coagulation system were within the reference values. The thromboelastography parameters did not deviate from the reference values for the parameters. According to the results of the thrombodynamics study, the average value of the initial clot growth rate among all patients was increased and amounted to 58.3±5.07 μm/min, the steady-state velocity also increased among all patients to 29.5±4.3 μm/min, the median and the mean values of the remaining parameters were within the reference intervals. Conclusion: the parameters of standard coagulogram and thromboelastography tests in pediatric PV patients had no deviations. The average values of thrombodynamics (initial and steady-state clot growth rate) were increased, which potentially indicates the hypercoagulation.